


the onesie

by Julx3tte



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alternate Universe - College/University, F/M, Fluff, Halloween Costumes
Language: English
Status: Completed
Published: 2020-09-29
Updated: 2020-09-29
Packaged: 2021-03-08 03:28:44
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,848
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26719054
Author URL: https://archiveofourown.org/users/Julx3tte/pseuds/Julx3tte
Summary: in which sylvain thinks about what costumes ingrid might wear for halloweenbased on art here:https://twitter.com/whimsycottt/status/1310413762269032449
Relationships: Ingrid Brandl Galatea/Sylvain Jose Gautier
Comments: 14
Kudos: 38





	the onesie

**Author's Note:**

> For @whimsycottt, and this comic
> 
> Ty to sylvgrid artists ;_;
> 
> Beta’d by floof master sunni & lance

The end of September was undoubtedly Sylvain’s favorite time of the year. Excluding his birthday, and Ingrid’s birthday, and maybe the new year too, the end of September marked the start of fall and the coming of his favorite holiday: Halloween.

Sylvain sighed happily as he walked through the grocery store aisle and the familiar bags of halloween candy. He grabbed one filled with chocolate as a treat before the real festivities began (and as an offering to Ingrid) as he finished his grocery store run.

In the car, as he put his bags in the car, a particular thought struck him like a jolt of electricity, sending a faint blush to his cheeks.

This was his first year being together with Ingrid, and his first year celebrating Halloween as a couple. They’d probably go to Dedue’s party together, arm in arm - and maybe even coordinate costumes.

And, as Sylvain allowed himself to think about, their relationship unlocked an entire swath of costume options for them. Including the sexy ones.

Grinning to himself, Sylvain sent a picture of the candy to Ingrid. 

_ trick or treat ;) _

_ a bit early don’t u think? _

_ Gotta plan costumes ahead or the good ones will be gone _

_ Mmmmmmm : ) _

Sylvain put his phone away and drove home to the thought of Ingrid in different halloween costumes.

Would she be an angel - complete with a false, pipe cleaner halo, feathered angel wings, a tight bikini top and white stockings… He could imagine it already, a little Ingrid perched on his shoulder telling him  _ not _ to ruin his chances at a good holiday gift during the spookiest time of the year. Maybe he’d get a peck on the cheek if he were extra good. Or maybe even a kiss on the lips if he were  _ extra  _ good.

She’d make a fantastic witch, too - a miniskirt and crop top, and a long shawl. Sylvain could imagine her cackle - maybe she’d tie him up and use him for a potion. He’d sit in her cauldron all day if that meant he could admire the soft skin of her abdomen and legs...

The possibilities, Sylvian decided, were endless now that they were in a relationship. He silently thanked his past self for mustering up the courage to finally ask her out and tried to focus on the task at hand. As his luck would have it, it wasn’t enough to have a distractingly beautiful girlfriend, but  _ now _ he had  _ ideas…  _ Ideas including imagining Ingrid in a variety of costumes, some elaborate and some achingly simple.

By the time he got home, he was ready to jump Ingrid on the spot. He got the groceries sorted away before she got home, leaving a small bowl of candy out on the coffee table, and sat on the couch, lost in his own imagination. There was no point in fighting it anymore.

A sexy cat. Ingrid could be a sexy cat. He could see it already: fake fur ears on a headband, and large fur cat paw gloves that he’d pull off her the second he got her alone. Maybe he could convince her to put on a false tail, though that was doubtful.

By the time the door opened and Ingrid got home from class, headphones on, Sylvain’s eyes jumped to her, still dazed from the epiphany he was having of Ingrid in Halloween costumes.

There wasn’t a time when he didn’t think Ingrid looked incredible, but after picturing her in sexy halloween costumes all afternoon, the sight of her so modest - coming home from class in leggings and a big hoodie - sent a flash of heat through his chest. He bit his lip and threw his phone onto the side of the couch.

Ingrid quirked an eyebrow at him, took off her shoes, and dropped her headphones around her neck.

“Doing okay there, Sylvain?” she asked.

Sylvain stood, walking as saucily as he could manage. “Just thinking,” he said, walking up within arm’s reach. 

Ingrid held her ground and tried to hide the smirk growing on the corners of her mouth. “Thinking about what?”

“It’s nearly Halloween, Ing. I love Halloween.”

Then Sylvain leaned in to kiss her, hands wrapping around her back to draw her close. Her fingers tangled into his hair and his body relaxed at the touch.

They broke their kiss and Sylvain immediately picked her up and started walking back towards the couch, Ingrid flailing against him, cheeks flushed.

“Sylvain! What are you doing?”

“Trick or treat dear,” he replied, throwing her onto the couch and joining her. He tilted Ingrid’s head to the side so he could whisper in her ear. “And I choose a treat.”

* * *

The thoughts of Ingrid in sexy halloween wear didn’t go away through the month of October. If anything, they got worse as they shopped for halloween costumes and figured out what they needed to bring to Dedue’s party.

Every year, Dedue used Dimitri’s place to host Halloween. The man went all out, decorating various rooms by theme, setting up a pseudo haunted house in the backyard. 

This year, Dedue promised them a trick-or-treat experience, and Ingrid brightened up as soon as she found out. 

The night of the party, Sylvain could feel himself giddy with anticipation - not from the candy, or the party, but to see what costume Ingrid would come out wearing. It likely wouldn’t be as sexy as he imagined, not for the party, but at this point his imagination had gotten out of control.

The other day, he thought of him as a sexy ship’s captain and Ingrid as a mermaid, complete with a shell bra and a fake tail. He’d been trying to drop hints all month, too, and the suspicious packages that they’d been getting in the mail (that felt like clothing when he squeezed them and brought them inside) didn’t help his growing anticipation. 

“You ready to see?” Ingrid called out from the bedroom. She’d kicked him out while she changed, and Sylvain’s excitement only grew. 

He’d chosen a rather modest one this year - he was a sexy cop. Short shorts, handcuffs, and a cropped black vest made up the outfit, and Sylvain’s body did the rest. He got changed quickly before Ingrid got home from work, knowing that they’d head right to the party as soon as she got ready.

“Yes,” he replied. Then, to himself. “Yes please.”

Ingrid would probably go with something with a skirt. A maid, or maybe a sexy princess. Something with a jacket, since she ran cold, and hopefully something with a cropped top. 

Ingrid stepped out in a cotton candy blue unicorn onesie and his mind stopped short. It had wings and a rainbow tail, and was  _ laughably _ huge. Ingrid even had matching unicorn slippers on.

“Oh.”  _ Did his voice just crack? It did. It definitely did. _

“Like it?” she asked, shrugging so that the unicorn wings bounced up and down, and Sylvain could feel his spirits sink. Maybe he was being too indirect, suggesting she match him, or maybe he was reading the signs wrong. 

“It’s… cute,” he replied, laughing to himself.

“Hurry! Dedue is giving out full sized snickers!”

* * *

They got to the party just in time to make it through the first trick-or-treat run. Dedue set up the back yard as a trick-or-treat maze, and each section had a challenge to get past to earn candy. Ingrid figured out each one in record time.

She went through the maze twice, filling three pumpkin buckets worth of candy on her own, while Sylvain went inside the house to chat with the others. 

Regardless of his sexy expectations, it was always good to see his friends. Finding time outside of exams and work studies and research was getting thin, and any excuse was a good one to get together and party. And gossip.

Felix could see the disappointment in his friend’s face.

“Did you really think Ingrid would wear something sexy just because you’re dating?” he asked. “Last year she wore an inflatable whale costume, dude.”

Sylvain sighed. “Okay that’s fair.”

“When we were kids, she dressed up as a grizzly bear for three years in a row.”

“Okay, I get it Fel.”

“Just saying. Besides, did you actually tell her you wanted her to dress up in a revealing costume?”

“....no…” Sylvain said, grimacing internally.

“Dude.” Felix shook his head and walked over to Annette, who was setting up karaoke. “Just come sing.”

* * *

They came home from the party late and tired. Ingrid’s candy haul took all of their hands to get up the stairs to their apartment, and Sylvain had gotten cold, despite Ingrid having taken him by the arm during the short walk from the car. The onesie’s fake fur against his side helped him warm up a little, but not much. 

“Did you have fun, Sylvain?” Ingrid asked, setting the candy on the counter as Sylvain went to sit. Bundling up a blanket trying to get warm, he looked up at her from underneath it, hoping he could hide the involuntary pout on his face.

“Oh yeah, I got Dimitri to sing  _ My Heart Will Go On _ while you were in the maze.”

Ingrid raised an eyebrow. “Send me the video… by the way you look kind of down. What’s up?”

Leave it to Ingrid to notice. “Oh. Yeah, I think I set some expectations that weren’t very realistic about today,” he admitted, staring at his knees. 

Ingrid came over to sit next to him, tucking her arm under his through the blanket. 

“Like what?”

“I was hoping… ah, I’ve been thinking about you in a sexy costume all month but I never told you.”

“Ah.” Ingrid’s other hand moved to his chest, and she patted him affectionately as he continued. 

“And don’t get me wrong, the unicorn is cute, but I don’t really find unicorns that sexy? And that color is definitely...  _ not _ . But, you know, that’s not fair to make you dress up for someone else, even if we are dating, and I never said it.”

Ingrid cupped his cheek, and he finally noticed the wide grin on Ingrid’s face and the twinkle in her eye. Confused, Sylvain scrunched his face. “Are you laughing at me?”

“Sylvain,” Ingrid replied, kissing him on the cheek.

“Yes?”

“Did you really think this was the  _ only _ costume I had on?”

Sylvain’s mouth went into a wide ‘o’ as Ingrid stood up and unzipped the powder blue onesie. 

Ingrid had been wearing her hood up all night and Sylvain never noticed the headband keeping Ingrid’s hair back and out of her face, complete with two small devil’s horns.

As the onesie dropped, Sylvain’s eyes popped at the black leather bikini bottom, held together with rings on the side of her hips, and a strapless cupped bra. The black and red wings that made up part of her top bounced as Ingrid stepped out of the unicorn costume.

She fixed him with a sly grin and wiggled her eyebrows at him. “Trick or treat?” 

Sylvain had never stood up so fast in his life.


End file.
